This invention relates to energy and thermodynamic systems, and more particularly relates to componentry for enabling power sources, such as electric power sources, propulsion drives for, e.g., jet propulsion, and thermodynamic systems, such as cooling and ventilation systems, all that operate in high-efficiency and small-size regimes.
Compact, highly mobile, and efficient thermodynamic and energy systems are becoming increasingly important for a wide range of applications, such as powering and cooling of portable electronics, communications, and medical devices, control and modular propulsion of distributed and self-powered actuation and sensor systems, and thermodynamic cycling of distributed and/or auxiliary heating and ventilation systems, as well as many other applications. Typically, such applications optimally require power sources that are characterized by high power and energy density but minimal size and weight, and that are cost effective.
Historically, batteries, such as primary and rechargeable batteries, have been relied on for supplying portable, compact sources of power. Portable batteries are generally limited, however, to power production in the range of milliwatt to watts, and thus cannot conventionally address the need for significant as well as mobile and lightweight power production. The environmental incompatibility of typical batteries also poses a limitation for many applications.
Conversely, heat engines, such as gas turbine powered generators, can produce kilowatts of power at high power densities and efficiencies, but are typically of relatively large sizes that are not compatible with the high mobility requirement of many self- powered applications. Indeed, although the inherent high energy density of liquid fuels makes heat engines the most compact of all power sources, thermodynamic scaling and cost considerations have traditionally favored large size engines. Specifically, large engines, such as gas turbine engines, rely on high combustor exit temperatures and precise dimensional control to achieve high combustion and component efficiency; the cost and difficulty in achieving high component machine tolerances and accommodating high combustor temperatures in relatively smaller sized conventional engines have made the gas turbine a less attractive power source for power levels less than hundreds of kilowatts.
Beyond the dichotomy of power sources characterized by high power and energy density and those characterized by high mobility and low weight, systems for propulsion, circulation, heating, cooling, and other thermodynamic cycles are found to similarly be typically lacking in one or more requirements for efficiency, modularity, mobility, size, weight, or cost effectiveness that are characteristic of aggressive modern applications. Yet many aggressive portable and modular applications rely on the availability of both power and thermodynamic cycle sources that comply with such requirements. As a result, advances in mobile, self-powered, and small-scale systems have heretofore been limited.
The present invention overcomes limitations of conventional power and thermodynamic sources by providing micromachinery components that enable production of significant power and efficient operation of thermodynamic systems in the millimeter and micron regime to meet the efficiency, mobility, modularity, weight, and cost requirements of many modern applications.
Accordingly, in a first aspect, the invention provides a micromachine having a rotor disk journalled for rotation in a stationary structure by a journal bearing. A plurality of radial flow rotor blades, substantially untapered in height, are disposed on a first rotor disk face, and an electrically conducting region is disposed on a rotor disk face. A plurality of stator electrodes that are electrically interconnected to define multiple electrical stator phases are disposed on a wall of the stationary structure located opposite the electrically conducting region of the rotor disk. A first orifice in the stationary structure provides fluidic communication with the first rotor disk face at a location radially central of the rotor blades, and a second orifice in the stationary structure provides fluidic communication with the first rotor disk face at a location radially peripheral of the rotor blades. An electrical connection to the stator electrode configuration is provided for stator electrode excitation and for power transfer with the stator electrode configuration as the rotor disk rotates.
In accordance with the invention, there can be provided a plurality of stationary radial flow vanes at the radial periphery of the rotor disk in the fluidic communication between the first rotor disk face and the second orifice in the stationary structure. The radial flow vanes are preferably substantially untapered in height. In one embodiment, the radial flow rotor blades, which are also substantially untapered in height, are tapered in thickness as a function of radius to produce selected radial flow streamlines of fluid flowing between the blades.
In one embodiment provided by the invention, the rotor disk is of a material that is characterized by a strength-to-density ratio that enables a rotor speed of at least about 500,000 rotations per minute. In a further embodiment provided by the invention, the first orifice is characterized as providing fluidic communication of a first pressure, and the second orifice is characterized as providing fluidic communication of a second pressure that is greater than the first pressure.
The electrically conducting region of the rotor disk can be provided as, e.g., an electrically isolated annular conducting region on a second rotor disk face; or in another example, as a plurality of conducting regions, each conducting region being disposed on a rotor blade and electrically isolated.
As provided by the invention, the radial journal bearing can be provided as a gas journal bearing. There can be provided a thrust bearing between the first rotor disk face and an opposite wall of the stationary structure, and similarly, there can be provided a thrust bearing between the second rotor disk face and an opposite wall of the stationary structure.
The invention provides an embodiment of the micromachine as a micromotor-compressor configuration. The micromotor-compressor has a rotor disk journalled for rotation in a stationary structure by a journal bearing. A plurality of radial flow rotor blades, substantially untapered in height, are disposed on a first rotor disk face, and an electrically conducting region is disposed on a rotor disk face. A plurality of stator electrodes that are electrically interconnected to define multiple electrical stator phases are disposed on a wall of the stationary structure located opposite the electrically conducting region of the rotor disk. A first orifice in the stationary structure provides a low-pressure air inlet in fluidic communication with the first rotor disk face at a location radially central of the rotor blades, and a second orifice in the stationary structure provides a compressed air outlet in fluidic communication with the first rotor disk face at a location radially peripheral of the rotor blades. A radial outflow diffuser is provided in the fluidic communication between first rotor disk face and the second orifice. An electrical connection to the stator electrode configuration is provided for stator electrode excitation and for power transfer with the stator electrode configuration as the rotor disk rotates.
The invention provides, in the micromotor-compressor configuration, for the radial flow rotor blades to be tapered, if desired, in thickness as a function of radius to increase angular momentum of air from the air inlet flowing radially peripheral between the rotor blades. The diffuser can be provided as a plurality of radial outflow diffuser vanes that are shaped as a function of radius to convert angular momentum of air flowing from the rotor blades radially peripheral between the diffuser vanes to a rise in static air pressure.
The invention also provides an embodiment of the micromachine as a microturbine-generator configuration. The microturbine-generator has a rotor disk journalled for rotation in a stationary structure by a journal bearing. A plurality of radial flow rotor blades, substantially untapered in height, are disposed on a first rotor disk face, and an electrically conducting region is disposed on a rotor disk face. A plurality of stator electrodes that are electrically interconnected to define multiple electrical stator phases are disposed on a wall of the stationary structure located opposite the electrically conducting region of the rotor disk. A first orifice in the stationary structure provides a low-pressure air outlet in fluidic communication with the first rotor disk face at a location radially central of the rotor blades, and a second orifice in the stationary structure provides a compressed air inlet in fluidic communication with the first rotor disk face at a location radially peripheral of the rotor blades. A plurality of stationary, annular, radial inflow vanes are provided in the fluidic communication between first rotor disk face and the second orifice in the stationary structure. An electrical connection to the stator electrode configuration is provided for stator electrode excitation and for power transfer with the stator electrode configuration as the rotor disk rotates.
The invention provides, in the microturbine-generator configuration, for the radial inflow vanes to be shaped, if desired, in thickness as a function of radius to accelerate flow and add swirl to air from the compressed air inlet flowing radially central between the vanes. The radial flow rotor blades can also be tapered in thickness as a function of radius, if desired, to remove swirl from and expand air flowing from the vanes radially inward between the rotor blades, to rotate the rotor disk.
There are many applications for the micromachines of the invention, in some cases providing a superior replacement for existing, more conventional devices, and in others, embodying new capabilities enabled by the micromachines"" designs and operational characteristics. For example, where the first orifice is configured as a low-pressure air inlet and the second orifice is configured as a compressed air outlet, the micromachine provides a micromotor-compressor configuration that can be adapted for micron-scale cooling applications such as microelectronic packaging.
Where the second orifice is configured as a compressed air inlet and the first orifice is configured as a low-pressure outlet, the micromachine provides a microturbine-generator configuration that can surpass the characteristics of the best conventional batteries in power-weight considerations. The microturbine-generator provides a power source that can be employed in a wide range of portable electric power applications such as portable electronic and communication devices, heaters, coolers, and other such applications. Arrays of microturbine-generators and micromotor-compressors provided by the invention can also be employed.
Other features, advantages, and applications of the invention will be apparent from the following description and accompanying figures, and from the claims.